An exploration programme was conducted in the Damkhy limestone (Bahiya Coquina unit) of the Al Hasa phosphorite formation, which totals 1.3km 2. The geological mapping indicates that the most abundant rock type is limestone in Bahiya Coquina. Reserves of pure limestone, ranging between 93.39% and 99.28% CaCO 3, are estimated at about 39m. tonnes. The pure limestone mine life is estimated at 37.5 years based on a production of 550,000 tpa.
The Al Hasa formation, which covers the majority of the area, consists of limestone, coquina (fossiliferous limestone) and marl beds, in addition to locally charts and phosphate. The formation is subdivided into four members from bottom to top: Sultani phosphorite, Siwaqa limestone (Coquina), Bahiya limestone (Coquina) and Qatraneh. The total thickness of this formation is 65 metres.
The Qatrana Phosphorite consists of phosphatic chert, chert, phosphatic limestone, marly limestone and marl. The Bahiya Coquina unit is deposited between the two units of Sultani Phosphorite and Qatrana Phosphorite. Ranging 3-30 metres, it consists of oyster rich shelly limestone (Ostrea and Oxogyra) and is characterised by vertical and lateral changes in thickness and lithology.